This invention relates to a buckle for a seat belt, more specifically to an improved buckle design which provides superior impact resistances insuring the buckle remains latched during rapid changes in acceleration and deceleration.
Early seat belt buckle designs primarily were designed as a device to secure an occupant to prevent the occupant from impacting against the interior dash and steering wheel and to prevent ejection from the vehicle. Later designs of seat belt assembly employed more sophisticated seat belt retractors and pre-tensioning devices that could tighten a belt so as to securely and firmly pull the occupant against the seat back at the onset of a crash or even just prior to a crash event based on a sensed response to a rapid deceleration of a vehicle.
These added features created high acceleration and deceleration of the moveable components internal of the seat belt buckle assembly. Most seriously this inertia or momentum change could cause elements latching the tongue of the seat belt to the buckle to release, allowing the buckle under some circumstances to prematurely unlatch.
In U.S. Pat. No. 6,266,855 B1 a seat belt buckle was described which addressed this issue. This early attempt provided several solutions to the inertial movement of internal components and was a superior design to the buckles of that time.
The main disadvantage of this prior art design was the complexity of assembly and its requirement that the structural frame had to be made as a two-part assembly in order to properly secure the internal components. This added both to the design's complexity and cost.
The belt buckle of the present invention is a marked improvement in design eliminating these structural issues while providing a stronger yet less expensive assembly that provides secure locking of the latching mechanisms during occurrences of high inertial accelerations and decelerations, thus keeping the occupant secured in the seat belt harness.
In one embodiment, the inventions includes: an improved seat belt buckle assembly for use with a tongue of a seat belt, the seat belt buckle assembly has a frame; a latch attached to the frame which is moveable from a latched position to an unlatched position, a forward portion of the latch is configured to engage a portion of the tongue inserted into the frame as the latch moves into the latched position. A moveable control lever is positioned above the latch. The control lever is substantially U shaped, having a central portion with two lever arms extending from opposite ends of the central portion. The central portion of the control lever has a contact surface contacting an upper surface portion of the latch and a projecting tab extending from the central portion for receiving an upper spring. A locking bar is connected to the control lever and is moveable in L-shaped slots on each vertical side of the frame; wherein the latch is moved into engagement of the inserted tongue by an initial downward movement of the locking bar in the L-shaped slots followed by horizontal forward movement causing the control lever to pivot about the locking bar pushing the latch into a latched position. An upper spring urges the control lever and locking bar to push the latch downwardly into the latched position. An ejector is slidably mounted in the bottom of the frame for ejecting the tongue. The ejector is moveable in a horizontal direction within the frame. A mass is moveable with the ejector. A lower spring for biasing the ejector in an outward direction is connected to the frame and the mass. The lower spring compresses relative to the frame. When a release button which is slidably mounted onto the frame moves or pushes the locking bar in the L-shaped slots to unlatch the latch, and as the release button is depressed, the latch moves upwardly allowing the ejector and the mass to move forward, ejecting the tongue from the buckle. The control lever has stop surfaces on each end of the lever arms that move downwardly as the locking bar moves into a vertical portion of the L-shaped slots allowing the latch to move in the unlatched position, during normal use, locking the latch and control lever in the unlatched position, but when the buckle is latched and exposed to a rapid deceleration the mass slides compressing the lower spring into the frame moving the mass to occupy the space directly under the stop surfaces of the control lever arms of the control lever, blocking downward movement and preventing the locking bar from leaving a horizontal portion of the L-shaped slots, preventing movement of the latch into the unlatched position.
The upper spring is compressible between a rear fixed bracket attached to the frame and the tab of the control lever, wherein in the unlatched position the upper spring is compressed as the control lever rests on an upper surface of the latch when the locking bar is moved into the vertical portions of the L-shaped slot. The upper spring is held in place at each forward and rear end, the rear end held by a cylindrical projection concentrically inside the spring and the forward end held by the projecting tab on the control lever eccentrically holding the upper spring extending inside an upper portion of the upper spring and providing a downward force on the control lever and latch to assist movement in the L-shaped slot upon tongue insertion while allowing the upper spring to bend along a non linear path.
The mass is preferably attached to the ejector, the ejector fits into a slot in the mass and extends into a pair of horizontal slots on the frame, one horizontal slot being on each vertical side of the frame. The ejector secures the mass in the frame, limiting the mass to horizontal forward and rearward sliding movements.